// 监听元素高度变化
export default {
  bind(el, binding) {
    // el为绑定的元素，binding为绑定给指令的对象
    let width = '', height = '';
    function isReize() {
      const style = document.defaultView.getComputedStyle(el);
      if (width !== style.width || height !== style.height) {
        // 关键(这传入的是函数,所以执行此函数)
        binding.value({ width: style.width, height: style.height });
      }
      width = style.width;
      height = style.height;
    }

    el.__vueSetInterval__ = setInterval(isReize, 300);
  },

  unbind(el) {
    clearInterval(el.__vueSetInterval__);
  }
}